Methods and devices for anchoring suture in bone

ABSTRACT

An elongate rigid suture anchor is provided which is driven and impacted directly into bone. It has two ends, a distal end, which forms a hole in the bone, and a proximal end that penetrates the sidewall of the bone hole as the anchor is displaced proximally in the hole. A proximal force is applied to the suture anchor to displace the anchor proximally and cause tilting of the anchor. As the anchor is displaced proximally, the proximal end of the anchor enters obliquely into the sidewall of the hole.

BACKGROUND

Suture anchors are used to anchor suture in various medical proceduressuch as glenoid labrum and rotator cuff surgery. The suture anchor isanchored into bone and one or more sutures are coupled to the sutureanchor to hold the sutures in their intended position.

The present invention is directed to new methods and devices foranchoring sutures in bone.

SUMMARY

In one aspect of the present invention, a suture anchor is providedwhich has a sharp distal end that forms the tip of the suture anchorassembly. The sharp distal end of the suture anchor is driven into bonedirectly to form a hole in the bone. As such, the suture anchor itselfmay act like a bone punch or a bone drill, which obviates the need for aseparate device in a number of aspects of the present invention. Thesuture anchor is mounted to an introducer and is released once thesuture anchor has been driven to the desired depth. The introducer isthen withdrawn leaving the anchor impacted in the depth of the hole asfurther described below. Traction is then applied to the suture causingthe anchor to move proximal in the hole and tilt. The tilting causesboth the proximal and distal ends to engage the sidewall of the hole onopposing sides of the hole. Sidewall engagement holds the anchor in thehole. The pull-out resistance of the anchor in the hole is providedprimarily by penetration of the proximal end into the sidewall in oneaspect of the invention. Since the proximal end acts like a “spike” inthe bone, the anchor may not have to be “tilted” as much as prior artanchors, which typically tilt 90 degrees, and may tilt less than 45degrees.

In another aspect of the invention, the proximal end of the sutureanchor penetrates the sidewall of the hole further than the distal endpenetrates the sidewall. Many conventional suture anchors attempt toanchor tilting-type anchors with both ends penetrating the sidewall ofthe hole about the same amount. The proximal end of the suture anchormay be driven into the sidewall of the hole so that at least half of alength of the suture anchor is driven into the sidewall along a side ofthe suture anchor. Stated another way, the suture anchor is driven intothe sidewall so that at least part of a midsection of the anchorpenetrates the sidewall with the midsection being a transverse planelying halfway between the proximal and distal ends. While the proximalend may be preferentially driven into the bone, the distal end may notpenetrate bone as much as the proximal end. Stated still another way,the proximal end may penetrate the bone a transverse distance which isat least three times larger than a transverse distance that the distalportion penetrates bone. In still another aspect of the presentinvention, a distance (measured along the longitudinal axis of theanchor), which the proximal end is driven into bone is at least threetimes larger than a distance (also measured along the longitudinal axisof the anchor) that the distal end is driven into bone.

In still another aspect of the present invention, the suture anchor maybe formed in relatively small sizes so that the maximum outer transversedimension of the anchor no more than four times the nominal USP diameterof the suture coupled to the suture anchor Stated another way, when aplurality of sutures are attached to the anchor, the sum cross-sectionalarea of the sutures is at least 20% of the hole cross-sectional area (orthe maximum bone anchor cross-sectional area).

These and other aspects of the present invention will become apparentfrom the following description of the preferred embodiments, drawingsand claims

The details of one or more embodiments of the invention are set forth inthe accompanying drawings and the description below. Other features,objects, and advantages of the invention will be apparent from thedescription and drawings, and from the claims.

DESCRIPTION OF DRAWINGS

FIG. 1 shows a suture anchor mounted to an introducer.

FIG. 2 shows a suture anchor mounted to another introducer.

FIG. 3 shows the suture anchor.

FIG. 4 shows another view of the suture anchor.

FIG. 5 is a cross-sectional view of the suture anchor.

FIG. 6 is a cross-sectional view of another suture anchor.

FIG. 7 shows the suture anchor driven into bone to form a hole.

FIG. 8 shows the introducer removed and the view rotated 45 degreesrelative to FIG. 7.

FIG. 9 shows the suture anchor moved proximally within the hole untilthe proximal end contacts the sidewall of the hole.

FIG. 10 shows the suture anchor displaced proximally within the hole sothat the proximal end penetrates the sidewall of the hole and beginstilting.

FIG. 11 shows the suture anchor tilted further.

DETAILED DESCRIPTION

Referring to FIGS. 1-5, a suture anchor 2 and a suture anchor deliverysystem 4 are shown. The suture anchor 2 is mounted to a distal end 6 ofan introducer 8. One or more sutures 10 are coupled to the suture anchor2 and extend through a lumen 12 in the introducer 8. A suture lock 14 ispositioned at the proximal end of the introducer 8 to maintain tensionon the suture 10. Suture tension may be used to hold the suture anchor 2at the end of the introducer 8 as described in further detail below. Thesuture anchor 2 may be held at the distal end of the introducer 8 usinganother removable suture (not shown) or any other suitable releasableconnection without departing from numerous aspects of the present theinvention. The introducer 8 of FIG. 1 has a lumen 9 (see FIG. 5), whichreceives the suture 10. Alternatively, another introducer 8A is shown inFIG. 2 which has a slot 11 on an exterior surface in which the suture 10resides. The particular introducer 8, 8A is selected depending upon theparticular suturing procedure which will be undertaken by the user. Useof the introducer 8 is essentially the same as use of the introducer 8Aand discussion of one is equally applicable to use of the other.

The suture anchor 2 has a tip 16 at a distal end 5 so that the sutureanchor 2 may be directly driven into bone. The tip 16 has four beveledsides 18 that converge to form the tip 16. A shoulder 20 contacts thedistal end 6 of the introducer 8. The shoulder 20 is generally annularshaped and may have a slightly enlarged portion 22 along one side. Theshoulder 20 separates the suture anchor 2 into a proximal portion 22 anda distal portion 24. The distal portion 24 gradually increases incross-sectional area toward the shoulder 20. The suture anchor 2 may beformed from one piece of material so that the entire anchor isintegrally formed or at least the portions which engage bone such as theproximal and distal ends. The suture anchor 2 may include other parts,including movable or deformable parts, without departing from this andother aspects of the invention so long as those parts are not associatedwith bone engagement in this aspect of the invention. For example, theseparts may be associated with suture locking or release of the anchorfrom the introducer 8 rather than engaging bone. The suture anchor 2 maybe made of any suitable material such as metal, ceramic or a highstrength plastic. Of course, numerous aspects of the invention may bepracticed with the suture anchor 2 being made of numerous parts whichmay or may not be movable or deformable and which may or may not engagebone.

The anchor 2 is driven directly into bone as will be described infurther detail below. The anchor 2 itself forms the distal end of thedevice so that the anchor 2 forms the tip of a driver 23 which may actlike a bone drill or serves as a bone punch. As such, the deliverysystem 4 is simplified since the anchor 2 itself forms the penetratingtip of the driver 23. Many other prior art anchors are delivered into apre-drilled hole or are contained within the bone-hole forminginstruments, rather than forming the tip of the driver 23 itself. Theanchor 2 is driven directly into bone from the surface of the bone tothe desired depth. The anchor 2 is then released by simply releasing thesuture lock 14 and withdrawing the introducer 8 as described below. Thedistal portion 24 does not include a threaded exterior surface althoughvarious aspects of the present invention may be practiced with thedistal portion 24 having a threaded exterior surface. Some conventionalsuture anchors are rotated into threaded engagement with the bone whichmay prevent the suture anchor from having the ability to be withdrawnwithin the hole in the manner that the suture anchor 2 can be withdrawnas explained herein.

The distal portion 24 of the anchor 2 is designed to become impacted atthe bottom of the driven hole. To this end, the anchor 2 has an outersurface 26 that may form the largest transverse outer dimension of theanchor 2 and the introducer 8. The outer surface 26 may be sized largerthan the introducer 8 to facilitate withdrawal of the introducer 8. Whenthe anchor 2 is driven into bone, the outer surface 26 of the anchor 2is impacted at the bottom of the hole so that the anchor 2 isfrictionally engaged and held by the sides of the hole created by theanchor 2. The outer surface 26 is shown formed in four discrete partsbut may, of course, be a single continuous surface or may be formed withmore or fewer than four parts. The outer surface 26 may also be a formedin any other manner such as two relatively small areas on opposite sidesof the anchor so long as the opposing surfaces form the largest outerdimension of the anchor 2. The frictional engagement between the bottomof the hole and the outer surface 26 holds the anchor 2 so that thesuture 10 must be pulled with a reasonable force to overcome thisfrictional engagement and catching of the edge of the shoulder 20 asdescribed below in connection with use of the anchor 2. Prior artanchors which are advanced into a pre-drilled hole differ from thisaspect of the present invention since such anchors sit loosely at thebottom of the hole rather than being impacted against the sides of thehole, and therefore require a special supplemental mechanism fordeployment from the introducer tool or to initiate tilting of theanchor. As will be described above, the present invention may also bepracticed without deformable or movable mechanisms or barbs that engagebone which many prior art anchors require.

The proximal portion of the suture anchor 2 extends proximally from theshoulder 20 and may include a keyed portion 28 having an exteriorsurface 30 that matches an interior surface of the introducer 8 so thattorque may be transmitted from the introducer 8 to the suture anchor 2.The keyed portion may be a multi-faceted portion or may take any othersuitable shape, such as oval as shown in FIG. 4, without departing fromthe scope of the invention. Of course, the keyed portion 28 may not berequired if the anchor 2 is simply driven directly into the bone withoutrotation.

A proximal end 31 of the suture anchor 2 also has a sharp tip 32 topenetrate bone as described in greater detail below. One or more suturechannels 34 may extend through the proximal portion and communicate witha recess 36 in the distal portion of the anchor 2. The suture channel 34includes a slot 38 on one side, which permits the suture 10 to enter andleave the channel 34. Alternatively, the suture 10 when passing alongthe proximal portion may reside partially or completely in a slot orgroove in the most distal portion of the introducer, before proceedingproximally either into the lumen of the introducer or to a continuationof a slot on the side of the introducer without departing from the scopeof the invention. A knot 35 may be formed in the suture 10, or otherenlargement 11 on to the suture such as a metallic or polymer bead,clip, crimp, or other such attachment, to secure the suture 10 to theanchor 2. The knot 35 is positioned in the recess 36 with the ends ofthe suture 10 extending through the suture channel 34 and into the lumen12 of the introducer 8. An opening 37 in the distal portion 24 is incommunication with the recess 36 so that the suture 10 may bemanipulated to secure the suture anchor 2 to the suture 10 or to secureand position the enlargement 11 onto the suture 10 and into the recess36. The suture channel 34 may be positioned off-set relative to thecenter of gravity or geometric central axis CA (see FIG. 7) of theanchor 2 and the introducer 8 for the reasons described below inconnection with use of the anchor 2. Alternatively, the recess 36 may beswaged, welded or glued to prevent removal of the suture 10 from therecess 36 with or without the knot 35. Referring to FIG. 6, anothersuture anchor 2A is shown wherein the same or similar reference numbersrefer to the same or similar structure and all uses of the suture anchor2 or suture anchor 2A are equally applicable to the other. The recess36A may also include a curvilinear passage, which receives a slidingloop of the suture 10 with both ends passing through the suture channel34 and proximally into control of the user. Alternatively, the anchor 2may include a mechanism that permits unidirectional sliding of one ormore sutures 10. Such a mechanism may include movable or deformableparts that engage the suture 10 but are not intended to engage bone.

Use of the suture anchor 2 is now described with reference to FIGS.7-11. The suture anchor 2 is driven directly into bone from the surfaceof the bone to form a hole in the bone. The introducer 8 may be rotatedduring driving of the suture anchor 2 to aid in advancing the anchor 2into bone. The suture anchor 2 may also be driven into a pilot hole thatis smaller or less deep than full insertion depth or width withoutdeparting from numerous aspects of the present invention. The pilot holeis sized smaller than the outer surface 26 of the anchor 2 so that theanchor 2 is still being driven into the bone to create the fulltransverse dimension of the hole H where it resides and so that theanchor 2 is impacted at the bottom of the hole. The hole in which thesuture anchor 2 is positioned defines a longitudinal direction L and atransverse direction T that will now be used to described aspects of thepresent invention. Once the suture anchor 2 has been driven to thedesired depth, tension on the sutures is released by releasing thesuture lock 14 (see FIG. 1). Releasing tension on the suture 10 releasesthe suture anchor 2 from the introducer 8. The suture anchor 2 may becoupled to the introducer 8 in any other fashion such as a second sutureor a releasable connection such as a threaded connection between thesuture anchor 2 and introducer 8. The introducer 8 may then be removedleaving the suture anchor 2 and the sutures 10 within the hole as shownin FIG. 8. The anchor 2 is held at the bottom of the hole by frictionalengagement between the anchor 2 and the sidewall of the hole. Nosupplemental mechanism or component may be required to uncouple or expelthe anchor from the end of the introducer although one may be providedwithout departing from numerous other aspects of the present invention.The anchor 2 also does not require a stiffened suture or stiff metalliccable to uncouple or expel the anchor from the introducer 8 although,again, one may be provided without departing from the invention. Theanchor 2 sits within the hole without any engagement or contact of theproximal end 31 of the anchor 2 with the sidewall of the hole.

The suture or sutures 10 are then tensioned to produce a force on thesuture anchor 2 that tends to move the anchor 2 proximally within thehole. When tension is initially applied to the suture 10, the anchor 2resists movement due to the fact that the anchor 2 is impacted at thebottom of the hole. Upon application of sufficient tension on the suture10, the frictional force holding the suture anchor 2 caused byimpaction, and scraping of the corner of the shoulder 20, is overcomeand the suture anchor 2 moves proximally within the hole. The initialproximal movement occurs with tilting until the proximal end of thesuture anchor contacts the sidewall of the hole as shown in FIG. 9.Continued tension on the suture 10 causes the proximal end 31 (and thedistal end to a lesser extent) to penetrate the sidewall of the hole.The anchor 2 advantageously may not require movable or deformable partsto engage the wall of the hole which makes for a simpler assembly thansome prior art anchors which require deformable or actuated barbs or thelike to engage the hole prior to or in association with proximalmovement of the anchor 2. The anchor 2 also does not require aninsertion shaft, which is pushed against the anchor to deform the anchor2 or to move the proximal end 31 of the anchor 2 into engagement withthe wall of the hole, or is elastically bent to bias a portion of theanchor against the sidewall, or holds a proximal corner of the anchoragainst the sidewall during insertion. The anchor 2 also does not haveand does not require an elastic connection or cable that will bias theanchor into a tilted position as soon as the anchor becomes separatedfrom the introducer. The anchor 2 relies on the frictional engagementbetween the anchor 2 and the hole to initially resist the proximal forceapplied to the anchor by the suture 10. As mentioned above, the suturechannel 34 (see FIGS. 3-6) may be eccentrically positioned relative tothe central axis CA (see FIG. 7) of the anchor 2 and the introducer 8 sothat suture tension causes a moment to be applied to the suture anchor2, which causes the anchor 2 to tilt within the hole, in associationwith proximal displacement, as shown in FIG. 9. Once the suture anchor 2has tilted within the hole, the distal portion 24 may also penetrate thesidewall somewhat but much less than the proximal end. The distalportion 24 is relatively large compared to the proximal portion 22 sothat the distal portion 24 does not easily penetrate bone when tensionis applied to the sutures 10. The present invention has been describedwithout use of a pusher to release the anchor or initiate tilting,however, numerous aspects of the present invention may be practiced witha pusher or insertion shaft without departing from the scope of theinvention. A portion 35 of the shoulder 20 may penetrate the sidewall ofthe hole on the same side of the hole as the proximal end 31 of theanchor 2 and may serve as somewhat of a “stop” as the proximal end 31 isdriven into the sidewall (see FIG. 11).

The proximal end 31 of the suture anchor 2 is driven into the bone likea “spike” which differs from many conventional anchors, which attempt toanchor both ends into bone somewhat equally rather than primarily theproximal end. The proximal end may tilt at an angle of less than 45°,which also differs from many conventional anchors that generally aretilted about 90 degrees. The proximal end 31 may be driven into thesidewall of the hole so that at least half of a length L (see FIG. 7) ofthe suture anchor 2 penetrates or intersects with the sidewall on atleast one side of the suture anchor 2 as shown in FIG. 11. Statedanother way, the suture anchor 2 is driven into the sidewall so that atleast part of a midsection 33 penetrates or intersects the sidewall. Themidsection 33 is a transverse cross section, which lies halfway betweenthe proximal and distal ends. Stated still another way, the sutureanchor 2 is driven into the sidewall a distance TD1 that is equal to atleast half the length L of the suture anchor 2. While the proximal end31 is preferentially driven into the bone, the distal portion 24 doesnot penetrate bone as much as the proximal portion 22 due to the largercross-sectional size of the distal portion, and the larger surface areathat presents against the sidewall. As such, the proximal portion 22 maypenetrate the bone with the transverse distance TD1 being at least threetimes larger than a transverse distance TD2 that the distal portion 24penetrates bone. In still another aspect of the present invention, adistance 23 (measured along the longitudinal axis of the anchor 2) whichthe proximal end 31 is driven into bone is at least three times largerthan a distance 25 (also measured along the longitudinal axis of theanchor 2) that the distal end is driven into bone. As mentioned below,the proximal and distal ends 22, 24 may in some circumstances, such aslow bone density, penetrate the bone in a relatively equal mannerwithout departing from other aspects of the present invention.

The suture anchor 2 displaces by design farther proximally in its hole,in the course of finding anchorage in bone, than do many other sutureanchors. The proximal displacement is relative to the insertion holetransverse diameter. In other anchors that have their locking mechanismsbiased against the sidewall with elastic or insertion-tools, or bynotches in the sidewall, immediate engagement with the side-wall ismade, preventing the anchor from displacing proximally in the hole. Thesuture anchor 2 may function somewhat differently in that the anchor mayslide against the sidewall with the anchor 2 sliding at least one holediameter and may even slide at least two hole diameters in some aspectsof the invention. The suture anchor 2 may tilt at an angle of less than45°, and may tilt as little as shown in FIG. 10 when in hard bone,although greater tilting may be accomplished without departing from theinvention. With progressive sliding and penetration, the angle ofpenetration increases, as does the resistance to continued sliding andtilting.

The suture anchor 2 of the present invention may also be formed inrelatively small sizes so that the outer surface 26, which representsthe maximum outer transverse dimension of the anchor 2, is no more than0.080 inch and may be, for example, about 0.062 inch. Stated anotherway, the suture anchor 2 may have a maximum outer transverse dimension(which is the outer surface in the preferred embodiment) that is no morethan four times the nominal USP diameter of the suture 10. This smallsize is made possible because the design may be a single piecefabrication without moveable parts or elastic elements, and thus can bemade in small sizes.

The suture anchor 2 has special characteristics that allow the use ofrelatively large sutures attached to the anchor 2. The design makespossible using attached sutures with nominal sum total cross sectionalarea of at least 20% of the anchor maximum cross sectional area when aplurality of sutures are coupled to the suture anchor. The anchormaximum cross sectional area is generally represented by a disc having adiameter equal to transverse dimension of the distal portion adjacent tothe shoulder. As an example, an anchor of 0.063 inch transversedimension can accommodate a double strand of USP No. 2 suture, USP No. 2suture having a nominal diameter of 0.020 inch.

Having relatively large sutures attached to the anchor is beneficial toclinical application because a relatively small transverse dimensionsuture anchor may be affixed to a strong and thick suture. The smallentry hole of the suture anchor inflicts less volume damage on the bone,and allows closer proximity of multiple anchors. The thicker suture isgenerally stronger and is less inclined to cut through the soft tissuestructures being repaired.

Integration of multiple aspects of the invention makes the use ofrelatively large suture size and small suture anchor possible. Thesuture recess 36 is positioned in the distal portion, where there issufficient space to accommodate the enlargement 11 on the suture. Thesuture channel 36 in the proximal portion allows passage of largesutures within the introducer adjacent to the proximal portion. Adeployment tool is absent in the introducer lumen, making space forlarge sutures compared to some anchors, which require a deploymentmechanism or tool. Absence of a deployment tool also allows for greatermaterial cross section of the introducer, allowing the introducer todeliver the forces necessary for driving the anchor into bone withoutpre-drilling. The shape of the distal portion leads to impaction of theanchor at the conclusion of the driving step, allowing the introducer tobe withdrawn away from the anchor without a supplemental deploymenttool. In the slotted configuration of the introducer, the self-deployingnature of the anchor is again essential, because the slot precludes alumen in the introducer for passage of a deployment tool. Relativelylarge suture size, especially in suture anchors that are self-driving,is a difference between some aspects of the present invention and manyconventional anchors.

The differential sizes and shapes of the proximal and distal portions22, 24 of the suture anchor 2 are also an aspect of the invention. Thedistal portion 24 penetrates the bone to form the hole in the bone whilethe proximal portion 22 penetrates the sidewall of the hole that isformed. The transverse dimension of the distal portion 24 forms a bonehole having the same transverse dimension as the distal portion so thatthe anchor 2 is impacted at the bottom of the hole. The introducer 8, onthe other hand, may be slightly smaller than the hole. The impaction ofthe anchor 2 first functions to cause the anchor 2 to disengage out ofthe introducer 8 upon withdrawal of the introducer 8 without anyaccessory mechanism or deployment tool. The impaction secondly causessome resistance to a traction force subsequently applied to the suture,such that tension on the suture causes a tilting moment on the anchor 2when the suture is tensioned. The large transverse dimension andassociated surface area causes the distal portion 24 to slide againstthe sidewall, with minimal penetration of the sidewall, as the anchor 2is displaced retrograde in the hole. The proximal portion 22 has thesharp tip 31, presenting minimal surface area to the sidewall as itcontacts the sidewall, leading to penetration of the sidewall primarilyby the proximal portion 22. The onset of penetration, or catching, ofthe sidewall by the proximal end 31 is one aspect of the invention,because this causes the traction force on the suture to deliver a forceon the proximal end 31 directed into the sidewall. This force in turncauses further penetration and tilting of the anchor 2. The proximalportion 22 is of a smaller maximum transverse dimension than the distalportion, in order that there is space for the introducer that fits overthe proximal portion, the introducer being not substantially larger intransverse dimension than the distal portion. The smaller transversedimension of the proximal portion 22 also allows tilting of the anchor 2so that the proximal end 31 may engage and penetrate into the sidewallof the hole as the anchor 2 slides retrograde. The shoulder may bedesigned to make possible numerous functions of the anchor 2. Theshoulder may, of course, act as the contact surface for transferringforces from the introducer 8 to the anchor 2 during advancement of theanchor 2 in bone. The shoulder may also help initiate tilting by“catching” the sidewall of the hole during initial tensioning of thesuture. Finally, the shoulder may also act as a stop as the proximal endis driven into bone as described above. The shoulder criticallyintegrates with other design elements. The surface of the shoulder maybe at an angle to the anchor-axis different than 90° without departingfrom the invention, though 90° is consider to be an optimal angle. Thetaper of the distal portion also allows tilting of the anchor sufficientfor the proximal tip to touch against the sidewall and begin entry intothe sidewall of the hole. The smaller transverse dimension and smalltransverse tip cross section of the proximal portion 22 also allowspenetration by the proximal portion 22 more easily than by the distalportion 24, causing a tendency to slide against the sidewall by thedistal portion 24, and a tendency to penetrate the sidewall by theproximal portion 22.

The present invention has been described with reference to preferredembodiments, however, it is understood that numerous modifications couldbe made without departing from the scope of the invention. For example,in association with special bone morphology, both ends of the anchor maypenetrate the bone equally or relatively equally without departing fromaspects of the invention. The distal portion may be shaped inalternative ways to facilitate driving into bone, for example in a coneshape, or intersecting cone shapes, or with a shape having beveled sidesnumbering other than four, or having beveled sides each with a singleslope, or as a foreshortened spade-point drill.

1-18. (canceled)
 18. A suture anchor assembly, comprising: anintroducer; a suture anchor coupled to the introducer, the suture anchorhaving a distal portion and a proximal portion, the distal portionhaving a distal end shaped to penetrate bone, the proximal portionhaving a proximal end also configured to penetrate bone, the sutureanchor being coupled to the introducer so that the distal end isexposed, the distal end being configured to penetrate the bone to form ahole from the surface of the bone to a desired depth, the hole having asidewall; and means for tilting the suture anchor within the hole afterpenetrating the bone with the suture anchor, the tilting means causingthe proximal end to penetrate the sidewall of the hole on a sideopposite the sidewall where the distal end engages the sidewall.
 19. Thesuture anchor assembly of claim 18, wherein: the tilting means includesa suture coupled to the suture anchor, wherein the suture anchor tiltswithin the hole upon application of tension to the suture.
 20. Thesuture anchor assembly of claim 19, wherein: the suture anchor has amaximum outer transverse dimension; and the suture has a nominal USPdiameter; wherein the maximum outer transverse dimension of the anchoris no more than 4 times the nominal USP diameter of the suture.
 21. Thesuture anchor assembly of claim 18, wherein: the proximal and distalends of the suture anchor are formed integrally from a single piece ofmaterial.
 22. The suture anchor assembly of claim 18, wherein: thesuture anchor is formed so that all portions which engage bone areformed from the single piece of material.
 23. The suture anchor assemblyof claim 18, wherein: the suture anchor has no movable or deformableparts.
 24. The suture anchor assembly of claim 18, wherein: the sutureanchor has no movable or deformable parts which engage bone.
 25. Thesuture anchor assembly of claim 18, wherein: the introducer covers theproximal end of the suture anchor when the suture anchor is coupled tothe introducer, the proximal end being exposed when the introducer isremoved; and the tilting means including a suture which is tensioned tomove the proximal end of the anchor into contact with the sidewall ofthe hole.
 26. The suture anchor assembly of claim 18, wherein: thesuture anchor has a shoulder positioned at a transition between thedistal portion and the proximal portion,
 27. The suture anchor assemblyof claim 18, wherein: the distal portion of the suture anchor includes arecess sized to receive the suture.
 28. The suture anchor assembly ofclaim 27, wherein: the suture anchor includes a suture channel whichextends through the proximal portion, the suture channel communicatingwith the recess so that the suture may extend through the suture channelwhile the suture is positioned in the recess.
 29. The suture anchorassembly of claim 28, wherein: the suture channel is eccentricallypositioned so that an eccentric force is applied to the suture anchorwhen suture positioned in the suture channel is tensioned.
 30. Thesuture anchor assembly of claim 28, wherein: the suture channel includesa slot, the slot permitting suture to enter and leave the suturechannel.
 31. The suture anchor assembly of claim 27, wherein: the recessis sized to receive an enlargement on the suture.
 32. The suture anchorassembly of claim 18, wherein: the proximal portion tapers proximallyfrom a shoulder to the proximal end, the shoulder being a transitionbetween the proximal portion and the distal portion.
 33. The sutureanchor assembly of claim 32, wherein: the distal portion, the shoulderand the proximal portion are integrally formed.
 34. The suture anchorassembly of claim 18, wherein: the introducer has a lumen containingonly the suture.
 35. The suture anchor assembly of claim 34, wherein:the introducer has one lumen containing only the suture.
 36. A method ofinstalling a suture anchor, comprising the steps of: providing a sutureanchor having a proximal end and a distal end, the suture anchor beingmounted to an introducer; driving the suture anchor into a surface of abone to form a hole in the bone, the hole having a sidewall and alongitudinal axis, the hole defining a transverse axis which isperpendicular to the longitudinal axis; applying a force to the sutureanchor which tilts the suture anchor within the hole and causes theproximal end of the suture anchor to penetrate the sidewall of the hole.37. The method of claim 36, wherein: the applying step is carried out bytensioning a suture which is coupled to the suture anchor.
 38. Themethod of claim 36, wherein: the applying step is carried out so thatthe distal end of the anchor also penetrates the sidewall of the hole,the proximal end of the suture anchor penetrating the sidewall on anopposite side of the sidewall from where the distal end penetrates thesidewall of the hole.
 39. The method of claim 36, wherein: the drivingstep is carried out so that the anchor is impacted in the hole when thedriving step is completed.
 40. The method of claim 36, wherein: theproviding step is carried out with the anchor having no movable ordeformable parts.
 41. The method of claim 36, wherein: the suture anchorhas no movable or deformable parts which engage bone.
 42. The method ofclaim 36, wherein: the driving step is carried out with the distal endof the suture anchor penetrating a surface of the bone.
 43. The methodof claim 36, further comprising the step of: removing the introducer.44. The method of claim 36, wherein: the removing step exposes theproximal end of the suture anchor; and the applying step moves theproximal end of the anchor into contact with the sidewall of the hole.45. The method of claim 36, wherein: the applying step is carried outwith at least part of a midsection intersects the sidewall, themidsection being a cross-section of the suture anchor positioned midwaybetween the proximal end and the distal end.
 46. The method of claim 36,wherein: the applying step is carried out with the proximal end of thesuture anchor penetrating a transverse distance into the sidewall whichis at least three times more than a transverse distance that the distalend penetrates into the sidewall.
 47. The method of claim 36, wherein:the providing step is carried out by providing an introducer having adistal end, the suture anchor having a shoulder with the distal end ofthe introducer contacting the shoulder, a portion of the shoulderpenetrating the sidewall on a same side of the sidewall that theproximal end of the suture anchor penetrates the sidewall
 48. The methodof claim 36, wherein: the driving step is carried out so that the anchoris impacted in the hole.
 49. The method of claim 36, wherein: theapplying step is completed with the suture anchor tilting no more than45 degrees.
 50. The method of claim 36, wherein: the driving step iscarried out with the anchor being driven into a pilot hole which issmaller than the anchor so that the anchor forms the hole which islarger than the pilot hole.
 51. A method of installing a suture anchor,comprising the steps of: providing a suture anchor having a proximal endand a distal end which define a length of the suture anchor; driving thesuture anchor into bone to form a hole in a bone with the distal end ofthe suture anchor, the hole having a sidewall and a longitudinal axis,the hole defining a transverse axis which is perpendicular to thelongitudinal axis; applying a force to the suture anchor which displacesthe suture anchor proximally within the hole, the proximal end of thesuture anchor penetrating the sidewall of the hole. 52-101. (canceled)